The research conducted in this laboratory is directed towards furthering our understanding of auditory perceptual phenomena through a program of comparable experiments on listeners with impaired auditory systems and those with normal auditory systems. These experiments can be classified under three headings, perception of speech, perception of complex tones, and information processing. The speech-perception experiments are concerned primarily with studying confusions among nonsense syllables presented under various conditions of distortion (such as masking, filtering, or interruption). The complex-tone experiments deal primarily with studying the origins of perceptual phenomena associated with complex tones (such as remote masking, the residue pitch, and the cubic difference tone) by studying them among listeners whose auditory impairments rule out certain possible origins. The information-processing experiments attempt to study the approaches or strategies that listeners use in a given task and whether or not these strategies differ as a function of auditory impairment. These categories of experimentation are, of course, not independent of one another and investigation of the relations among the categories is an important part of the research program. These relations involve such things as the common mechaniss underlying both perception of speech and of complex tones as well as the ways in which measures of perception are influenced by individual differences in information processing.